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Please use this identifier to cite or link to this item: http://hdl.handle.net/10204/5701

Title: Multi-model forecast skill for mid-summer rainfall over southern Africa
Authors: Landman, WA
Beraki, A
Keywords: Southern Africa rainfall forecast
Seasonal forecasting
Probabilistic rainfall forecast skill
El Nino-Southern Oscillation
Issue Date: Feb-2012
Publisher: Wiley
Citation: Landman, WA and Beraki, A. 2012. Multi-model forecast skill for mid-summer rainfall over southern Africa. International Journal of Climatology, vol. 32(2), pp 303-314
Series/Report no.: Workflow;8590
Abstract: Southern African December-January-February (DJF) probabilistic rainfall forecast skill is assessed over a 22-year retroactive test period (1980/1981 to 2001/2002) by considering multi-model ensembles consisting of downscaled forecasts from three of the DEMETER models, the ECMWF, Meteo-France and UKMO coupled ocean-atmosphere general circulation models. These models are initialized in such a way that DJF forecasts are produced at an approximate 1-month lead time, i.e. forecasts made in early November. Multi-model forecasts are obtained by: i) downscaling each model’s 850 hPa geopotential height field forecast using canonical correlation analysis (CCA) and then simply averaging the rainfall forecasts; and ii) by combining the three models’ 850 hPa forecasts, and then downscaling them using CCA. Downscaling is performed onto the 0.5° × 0.5° resolution of the CRU rainfall data set south of 10° south over Africa. Forecast verification is performed using the relative operating characteristic (ROC) and the reliability diagram. The performance of the two multi-model combinations approaches are compared with the single-model downscaled forecasts and also with each other. It is shown that the multi-model forecasts outperform the single model forecasts, that the two multi-model schemes produce about equally skilful forecasts, and that the forecasts perform better during El Nino and La Nina seasons than during neutral years.
Description: Copyright: 2012 Wiley. This is the post-print version of the work. The definitive version is published in International Journal of Climatology, vol. 32, pp 303–314. doi: 10.1002/joc.2273
URI: http://onlinelibrary.wiley.com/doi/10.1002/joc.2273/full
ISSN: 0899-8418
Appears in Collections:Climate change
General science, engineering & technology

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